High-temperature composite corrosion inhibitor and preparation method thereof

Abstract

The invention relates to the field of corrosion inhibitors, in particular to a high-temperature composite corrosion inhibitor and a preparation method thereof, and aims to solve the problems that an existing corrosion inhibitor is limited in corrosion inhibition effect, poor in high-temperature stability and difficult to completely meet the anti-corrosion requirement in a high-temperature acid environment. The preparation method comprises the following steps: stirring and mixing a main corrosion inhibitor, an auxiliary corrosion inhibitor, molybdate, organic silicon, a film-forming agent, a surfactant, nano silicon dioxide and a solvent to obtain the high-temperature composite corrosion inhibitor. According to the preparation method, the formula of the high-temperature composite corrosion inhibitor is optimized, multi-scale synergistic protection is achieved through multiple action mechanisms, then the high-temperature composite corrosion inhibitor is endowed with the excellent corrosion inhibition effect, the excellent corrosion inhibition capacity can still be kept in the high-temperature environment, and then the excellent corrosion prevention effect on metal materials is achieved.

Description

Technical Field

[0001] This invention relates to the field of corrosion inhibitors, specifically to a high-temperature composite corrosion inhibitor and its preparation method. Background Technology

[0002] Acidizing technology, as an enhanced oil recovery measure, is one of the important means of increasing production and injection in oil and gas field development. However, during the application of acidizing measures, the acid solution can cause severe corrosion to downhole metal facilities and pipelines. Among various corrosion prevention methods, corrosion inhibitors are favored due to their advantages such as low dosage, low cost, good corrosion prevention effect, and wide applicability.

[0003] Conventional corrosion inhibitors have limited inhibitory effects, making it difficult to fully meet the corrosion protection requirements of harsh environments. Furthermore, they exhibit poor high-temperature stability, often decomposing and losing their inhibitory activity under high temperatures, thus failing to effectively resist the erosion of corrosive media. Therefore, developing a high-temperature composite corrosion inhibitor and its preparation method is of significant practical importance.

[0004] To address the aforementioned technical shortcomings, a solution is proposed. Summary of the Invention

[0005] In order to overcome the above-mentioned technical problems, the present invention aims to provide a high-temperature composite corrosion inhibitor and its preparation method, which solves the problems that existing corrosion inhibitors have limited corrosion inhibition effect and poor high-temperature stability, making it difficult to fully meet the anti-corrosion requirements in high-temperature acidic environments.

[0006] The objective of this invention can be achieved through the following technical solutions: A high-temperature composite corrosion inhibitor comprises the following components in parts by weight: The main corrosion inhibitor consists of 11-19 parts, the auxiliary corrosion inhibitor consists of 5-13 parts, the molybdate consists of 4-5 parts, the organosilicon consists of 2-4 parts, the film-forming agent consists of 3-5 parts, the surfactant consists of 0.9-1.5 parts, the nano silica consists of 2-3 parts, and the solvent consists of 40-50 parts. The primary corrosion inhibitor is prepared by the following steps. Step a1: 2-Trifluoromethyl-4-bromopyridine, 4,4'-bis(dimethylamino)benzyl alcohol, anhydrous potassium carbonate, deionized water, and N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Argon gas was introduced for protection, and the reaction was stirred for 20-30 min at a temperature of 20-25℃ and a stirring rate of 200-300 r / min. Then, tetra(triphenylphosphine)palladium was added and the temperature was raised to 100-105℃, and the reaction was stirred for 10-12 h. After the reaction was completed, the reaction product was added to a saturated saline solution, and then extracted 2-3 times with dichloromethane. The extracts were combined and the solvent was removed by rotary evaporation to obtain a fluorinated bis(tertiary) amine compound. Step a2: Add the fluorinated bis-tertiary amine compound, potassium hydroxide, and dimethyl sulfoxide to a three-necked flask equipped with a stirrer, thermometer, and constant-pressure dropping funnel. Stir the reaction at 20-25℃ and a stirring rate of 200-300 r / min for 20-30 min. Then, raise the temperature to 90-95℃ and continue stirring for 2-3 h. Then, add benzyl chloride dropwise while stirring, controlling the dropping rate to 1-3 drops / s. After the addition is complete, continue stirring for 10-15 h. After the reaction is complete, cool the reaction product to room temperature and add it to anhydrous tetrahydrofuran. After standing, the precipitate will precipitate. Then, vacuum filter the precipitate and place it in a vacuum drying oven at 60-65℃ for 2-3 h to obtain the main corrosion inhibitor.

[0007] In a preferred embodiment of the present invention, the ratio of 2-trifluoromethyl-4-bromopyridine, 4,4'-bis(dimethylaminobenzyl alcohol), anhydrous potassium carbonate, deionized water, N,N-dimethylformamide, and tetra(triphenylphosphine)palladium in step a1 is 10 mmol: 10 mmol: 15-20 mmol: 20-25 mL: 60-70 mL: 0.5-0.7 g.

[0008] In a preferred embodiment of the present invention, the ratio of the fluorinated bis-tertiary amine compound, potassium hydroxide, dimethyl sulfoxide and benzyl chloride in step a2 is 10 mmol: 22-25 mmol: 80-100 mL: 20 mmol.

[0009] In a preferred embodiment of the present invention, the auxiliary corrosion inhibitor is prepared by the following steps: Step b1: Add 3-bromo-1-propanol, triethylamine, and anhydrous tetrahydrofuran to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. Stir the reaction at 20-25℃ and 200-300 r / min for 20-30 min. Then, add phosphorus oxychloride dropwise while stirring, controlling the dropping rate to 1-3 drops / s. After the addition is complete, raise the temperature to 40-45℃ and continue stirring for 6-8 h. After the reaction is complete, cool the reaction product to room temperature, then filter under vacuum. Remove the solvent from the filtrate by rotary evaporation to obtain the tribromophosphate compound. Step b2: Add the tribromophosphate compound, 5-aminotetrazolium, triethylamine, and anhydrous acetonitrile to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection and stir at 0-5℃ and 200-300 r / min for 20-30 min. Then raise the temperature to 20-25℃ and continue stirring for 2-3 h. After that, raise the temperature to 80-85℃ and continue stirring for 5-6 h. After the reaction is complete, cool the reaction product to room temperature, then filter under vacuum. Remove the solvent by rotary evaporation of the filtrate, then wash it 2-3 times with anhydrous ethanol and anhydrous acetone in sequence. Finally, place it in a vacuum drying oven and dry it at 60-65℃ for 2-3 h to obtain the auxiliary corrosion inhibitor.

[0010] In a preferred embodiment of the present invention, the ratio of 3-bromo-1-propanol, triethylamine, anhydrous tetrahydrofuran and phosphorus oxychloride in step b1 is 35-40 mmol: 40-50 mmol: 60-70 mL: 10 mmol.

[0011] In a preferred embodiment of the present invention, the ratio of the tribromophosphate compound, 5-aminotetrazole, triethylamine and anhydrous acetonitrile in step b2 is 10 mmol: 30 mmol: 35-45 mmol: 80-90 mL.

[0012] As a preferred embodiment of the present invention, a method for preparing a high-temperature composite corrosion inhibitor includes the following steps: Step 1: Weigh out 11-19 parts of the main corrosion inhibitor, 5-13 parts of the auxiliary corrosion inhibitor, 4-5 parts of molybdate, 2-4 parts of organosilicon, 3-5 parts of film-forming agent, 0.9-1.5 parts of surfactant, 2-3 parts of nano silica, and 40-50 parts of solvent according to the following weight proportions, and set aside. Step 2: Add the main corrosion inhibitor, auxiliary corrosion inhibitor, molybdate, organosilicon, film-forming agent, surfactant, nano silica and solvent to a mixer and mix for 30-60 minutes at a temperature of 50-60℃ and a stirring rate of 800-1000r / min to obtain a high-temperature composite corrosion inhibitor.

[0013] In a preferred embodiment of the present invention, the molybdate is ammonium molybdate.

[0014] In a preferred embodiment of the present invention, the organosilicon is phenyl silicone oil DC-556.

[0015] In a preferred embodiment of the present invention, the film-forming agent is polyvinyl alcohol 1799.

[0016] In a preferred embodiment of the present invention, the surfactant is a mixture of sodium dodecylbenzenesulfonate and Tween-85 in a mass ratio of 1:2-3.

[0017] In a preferred embodiment of the present invention, the average particle size of the nano-silica is 30 nm.

[0018] In a preferred embodiment of the present invention, the solvent is a mixture of No. 200 solvent oil, ethylene glycol and deionized water in a volume ratio of 3-4:2-3:1.

[0019] Compared with the prior art, the beneficial effects of the present invention are: A method for preparing a high-temperature composite corrosion inhibitor involves mixing a primary corrosion inhibitor, an auxiliary corrosion inhibitor, molybdate, organosilicon, a film-forming agent, a surfactant, nano-silica, and a solvent to obtain the high-temperature composite corrosion inhibitor. This high-temperature composite corrosion inhibitor utilizes both the primary and auxiliary corrosion inhibitors to form a stable protective film on the metal surface. The primary and auxiliary corrosion inhibitors provide complementary protection, increasing the film density and effectively preventing direct contact between the corrosive medium and the metal surface, significantly improving the corrosion resistance of the metal material. Simultaneously, the molybdate can also form a passivation film on the metal surface. Organosilicon can improve the heat resistance and chemical stability of the corrosion inhibitor, maintaining good corrosion inhibition effect at high temperatures. Film-forming agents can further fill and improve defects in the protective film, surfactants can enhance the compatibility between components, and the addition of nano-silica can fill the pores of the protective film, improving the mechanical strength of the film through dispersion strengthening and reducing crack formation at high temperatures. This preparation method optimizes the high-temperature composite corrosion inhibitor formulation, utilizing multiple mechanisms to achieve multi-scale synergistic protection, thereby giving the high-temperature composite corrosion inhibitor excellent corrosion inhibition effect, and maintaining excellent corrosion inhibition ability in high-temperature environments, thus achieving excellent anti-corrosion effect on metal materials.

[0020] In the preparation of the high-temperature composite corrosion inhibitor, a primary corrosion inhibitor was first prepared. This was achieved by reacting 2-trifluoromethyl-4-bromopyridine with 4,4'-bis(dimethylamino)benzyl alcohol, where the bromine atom on 2-trifluoromethyl-4-bromopyridine reacts with the hydroxyl group on 4,4'-bis(dimethylamino)benzyl alcohol to obtain a fluorinated bis(tertiary)amine compound. Subsequently, this fluorinated bis(tertiary)amine compound was reacted with benzyl chloride, where the tertiary amine group on the fluorinated bis(tertiary)amine compound reacts with the chlorine atom on benzyl chloride to form a quaternary ammonium group, thus obtaining the primary corrosion inhibitor. The primary corrosion inhibitor contains two quaternary ammonium groups in its molecular structure. These quaternary ammonium groups carry a positive charge and can electrostatically adsorb onto the negatively charged sites on the metal surface caused by corrosion, thereby forming a stable fluorinated passivation film on the metal surface. This effectively prevents direct contact between the corrosive medium and the metal surface, significantly improving the corrosion resistance of the metal material. Simultaneously, the presence of fluorine, benzene rings, and pyridine rings endows it with excellent high-temperature resistance, further enhancing the high-temperature stability of the fluorinated passivation film and enabling it to maintain good corrosion inhibition effects even at high temperatures.

[0021] In the process of preparing the high-temperature composite corrosion inhibitor, an auxiliary corrosion inhibitor was also prepared. This was achieved through the reaction of 3-bromo-1-propanol and phosphorus oxychloride, where the hydroxyl group on 3-bromo-1-propanol reacts with the chlorine atom on phosphorus oxychloride to form a phosphate ester structure and simultaneously introduce bromine atoms, yielding a tribromophosphate compound. Then, through the reaction of the tribromophosphate compound and 5-aminotetrazole, the bromine atom on the tribromophosphate compound reacts with the amino group on 5-aminotetrazole, thereby introducing the tetrazolium ring into the phosphate ester structure, resulting in the auxiliary corrosion inhibitor. This auxiliary corrosion inhibitor contains phosphorus, oxygen, and nitrogen atoms in its molecular structure, enabling it to act as adsorption centers and adsorb onto the metal surface. It can also form complexes with metal ions, converting active corrosion sites into inert sites, thus achieving a good corrosion inhibition effect. Furthermore, the presence of phosphorus and nitrogen atoms endows it with excellent high-temperature resistance and flame retardant properties, ensuring that the protective film maintains structural stability at high temperatures and preventing cracking due to thermal motion. Attached Figure Description

[0022] To facilitate understanding by those skilled in the art, the present invention will be further described below with reference to the accompanying drawings.

[0023] Figure 1 This is a schematic diagram showing the corrosion rate test results of the high-temperature composite corrosion inhibitors in Examples 1-3 and Comparative Examples 1-3 of the present invention. Figure 2 This is a schematic diagram showing the corrosion inhibition rate test results of the high-temperature composite corrosion inhibitors in Examples 1-3 and Comparative Examples 1-3 of the present invention. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Example 1

[0025] This embodiment describes a method for preparing a high-temperature composite corrosion inhibitor, comprising the following steps: Step S1: 10 mmol of 2-trifluoromethyl-4-bromopyridine, 10 mmol of 4,4'-bis(dimethylamino)benzyl alcohol, 15 mmol of anhydrous potassium carbonate, 20 mL of deionized water, and 60 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Argon gas was introduced for protection, and the reaction was stirred at 20 °C and 200 r / min for 20 min. Then, 0.5 g of tetrakis(triphenylphosphine)palladium was added, and the temperature was raised to 100 °C and the reaction was stirred for another 10 h. After the reaction was completed, the reaction product was added to a saturated saline solution, and then extracted twice with dichloromethane. The extracts were combined and the solvent was removed by rotary evaporation to obtain a fluorinated bis(tertiary)amine compound. Step S2: 10 mmol of fluorinated bis-tertiary amine compound, 22 mmol of potassium hydroxide and 80 mL of dimethyl sulfoxide were added to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. The mixture was stirred at 20 °C and 200 r / min for 20 min. Then the temperature was raised to 90 °C and the mixture was stirred for 2 h. Then 20 mmol of benzyl chloride was added dropwise while stirring, with the dropping rate controlled at 1 drop / s. After the addition was completed, the mixture was stirred for 10 h. After the reaction was completed, the reaction product was cooled to room temperature and then added to anhydrous tetrahydrofuran. After standing, the precipitate was precipitated and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at 60 °C for 2 h to obtain the main corrosion inhibitor. Step S3: 35 mmol of 3-bromo-1-propanol, 40 mmol of triethylamine and 60 mL of anhydrous tetrahydrofuran were added to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. The mixture was stirred at 20 °C and 200 r / min for 20 min. Then, 10 mmol of phosphorus oxychloride was added dropwise while stirring, with the dropping rate controlled at 1 drop / s. After the addition was completed, the temperature was raised to 40 °C and the mixture was stirred for 6 h. After the reaction was completed, the reaction product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain the tribromophosphate compound. Step S4: 10 mmol of tribromophosphate compound, 30 mmol of 5-aminotetrazolium, 35 mmol of triethylamine and 80 mL of anhydrous acetonitrile were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 0 °C and 200 r / min for 20 min. Then the temperature was raised to 20 °C and the mixture was stirred for 2 h. After that, the temperature was raised to 80 °C and the mixture was stirred for 5 h. After the reaction was completed, the reaction product was cooled to room temperature and then vacuum filtered. The solvent was removed by rotary evaporation of the filtrate. The filtrate was then washed twice with anhydrous ethanol and anhydrous acetone. Finally, it was placed in a vacuum drying oven and dried at 60 °C for 2 h to obtain the auxiliary corrosion inhibitor. Step S5: Weigh out 11 parts by weight of the main corrosion inhibitor, 5 parts by weight of the auxiliary corrosion inhibitor, 4 parts by weight of the molybdate, 2 parts by weight of the organosilicon, 3 parts by weight of the film-forming agent, 0.9 parts by weight of the surfactant, 2 parts by weight of the nano-silica, and 40 parts by weight of the solvent, and set aside. The molybdate is ammonium molybdate; the organosilicon is phenyl silicone oil DC-556; the film-forming agent is polyvinyl alcohol 1799; the surfactant is a mixture of sodium dodecylbenzenesulfonate and Tween-85 in a mass ratio of 1:2; the average particle size of the nano-silica is 30 nm; the solvent is a mixture of No. 200 solvent oil, ethylene glycol, and deionized water in a volume ratio of 3:2:1. Step S6: Add the main corrosion inhibitor, auxiliary corrosion inhibitor, molybdate, organosilicon, film-forming agent, surfactant, nano silica and solvent to a mixer and mix for 30 minutes at a temperature of 50°C and a stirring rate of 800 r / min to obtain a high-temperature composite corrosion inhibitor. Example 2

[0026] This embodiment describes a method for preparing a high-temperature composite corrosion inhibitor, comprising the following steps: Step S1: 10 mmol of 2-trifluoromethyl-4-bromopyridine, 10 mmol of 4,4'-bis(dimethylamino)benzyl alcohol, 18 mmol of anhydrous potassium carbonate, 22 mL of deionized water, and 65 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Argon gas was introduced for protection, and the reaction was stirred at 22 °C and 250 r / min for 25 min. Then, 0.6 g of tetrakis(triphenylphosphine)palladium was added, and the temperature was raised to 102 °C and the reaction was stirred for 11 h. After the reaction was completed, the reaction product was added to a saturated saline solution, and then extracted twice with dichloromethane. The extracts were combined and the solvent was removed by rotary evaporation to obtain a fluorinated bis(tertiary)amine compound. Step S2: 10 mmol of a fluorinated bis-tertiary amine compound, 24 mmol of potassium hydroxide, and 90 mL of dimethyl sulfoxide were added to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. The mixture was stirred at 22 °C and a stirring rate of 250 r / min for 25 min. The temperature was then raised to 92 °C and the mixture was stirred for 2.5 h. Then, 20 mmol of benzyl chloride was added dropwise while stirring, with a dropping rate of 2 drops / s. After the addition was complete, the mixture was stirred for 12 h. After the reaction was completed, the reaction product was cooled to room temperature and then added to anhydrous tetrahydrofuran. The mixture was allowed to stand to precipitate, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at 62 °C for 2.5 h to obtain the main corrosion inhibitor. Step S3: 38 mmol of 3-bromo-1-propanol, 45 mmol of triethylamine and 65 mL of anhydrous tetrahydrofuran were added to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. The mixture was stirred at 22 °C and 250 r / min for 25 min. Then, 10 mmol of phosphorus oxychloride was added dropwise while stirring, with the dropping rate controlled at 2 drops / s. After the addition was completed, the temperature was raised to 42 °C and the mixture was stirred for 7 h. After the reaction was completed, the reaction product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain the tribromophosphate compound. Step S4: 10 mmol of tribromophosphate compound, 30 mmol of 5-aminotetrazolium, 40 mmol of triethylamine and 85 mL of anhydrous acetonitrile were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 3°C ​​and 250 r / min for 25 min. Then the temperature was raised to 22°C and the mixture was stirred for 2.5 h. After that, the temperature was raised to 82°C and the mixture was stirred for 5.5 h. After the reaction was completed, the reaction product was cooled to room temperature and then vacuum filtered. The solvent was removed by rotary evaporation of the filtrate. The filtrate was then washed twice with anhydrous ethanol and anhydrous acetone. Finally, it was placed in a vacuum drying oven and dried at 62°C for 2.5 h to obtain the auxiliary corrosion inhibitor. Step S5: Weigh out 15 parts by weight of the main corrosion inhibitor, 9 parts by weight of the auxiliary corrosion inhibitor, 4.5 parts by weight of the molybdate, 3 parts by weight of the organosilicon, 4 parts by weight of the film-forming agent, 1.2 parts by weight of the surfactant, 2.5 parts by weight of the nano-silica, and 45 parts by weight of the solvent. The molybdate is ammonium molybdate; the organosilicon is phenyl silicone oil DC-556; the film-forming agent is polyvinyl alcohol 1799; the surfactant is a mixture of sodium dodecylbenzenesulfonate and Tween-85 in a mass ratio of 1:2.5; the nano-silica has an average particle size of 30 nm; and the solvent is a mixture of No. 200 solvent oil, ethylene glycol, and deionized water in a volume ratio of 3.5:2.5:1. Step S6: Add the main corrosion inhibitor, auxiliary corrosion inhibitor, molybdate, organosilicon, film-forming agent, surfactant, nano silica and solvent to a mixer and mix for 45 minutes at a temperature of 55°C and a stirring rate of 900 r / min to obtain a high-temperature composite corrosion inhibitor. Example 3

[0027] This embodiment describes a method for preparing a high-temperature composite corrosion inhibitor, comprising the following steps: Step S1: 10 mmol of 2-trifluoromethyl-4-bromopyridine, 10 mmol of 4,4'-bis(dimethylamino)benzyl alcohol, 20 mmol of anhydrous potassium carbonate, 25 mL of deionized water, and 70 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Argon gas was introduced for protection, and the mixture was stirred at 25 °C and a stirring rate of 300 r / min for 30 min. Then, 0.7 g of tetrakis(triphenylphosphine)palladium was added, and the mixture was heated to 105 °C and stirred for another 12 h. After the reaction was completed, the reaction product was added to a saturated saline solution, and then extracted three times with dichloromethane. The extracts were combined and the solvent was removed by rotary evaporation to obtain a fluorinated bis(tertiary) amine compound. Step S2: 10 mmol of a fluorinated bis-tertiary amine compound, 25 mmol of potassium hydroxide, and 100 mL of dimethyl sulfoxide were added to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. The mixture was stirred at 25 °C and a stirring rate of 300 r / min for 30 min. The temperature was then raised to 95 °C and the mixture was stirred for 3 h. Then, 20 mmol of benzyl chloride was added dropwise while stirring, with a dropping rate of 3 drops / s. After the addition was complete, the mixture was stirred for 15 h. After the reaction was completed, the reaction product was cooled to room temperature and then added to anhydrous tetrahydrofuran. The mixture was allowed to stand to precipitate, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at 65 °C for 3 h to obtain the main corrosion inhibitor. Step S3: 40 mmol of 3-bromo-1-propanol, 50 mmol of triethylamine and 70 mL of anhydrous tetrahydrofuran were added to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. The mixture was stirred at 25 °C and 300 r / min for 30 min. Then, 10 mmol of phosphorus oxychloride was added dropwise while stirring, with the dropping rate controlled at 3 drops / s. After the addition was completed, the temperature was raised to 45 °C and the mixture was stirred for 8 h. After the reaction was completed, the reaction product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain the tribromophosphate compound. Step S4: 10 mmol of tribromophosphate compound, 30 mmol of 5-aminotetrazolium, 45 mmol of triethylamine and 90 mL of anhydrous acetonitrile were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 5 °C and 300 r / min for 30 min. The temperature was then raised to 25 °C and stirred for 3 h. The temperature was then raised to 85 °C and stirred for 6 h. After the reaction was completed, the reaction product was cooled to room temperature and then vacuum filtered. The solvent was removed by rotary evaporation of the filtrate. The filtrate was then washed three times with anhydrous ethanol and anhydrous acetone. The filtrate was then placed in a vacuum drying oven and dried at 65 °C for 3 h to obtain the auxiliary corrosion inhibitor. Step S5: Weigh out 19 parts by weight of the main corrosion inhibitor, 13 parts by weight of the auxiliary corrosion inhibitor, 5 parts by weight of the molybdate, 4 parts by weight of the organosilicon, 5 parts by weight of the film-forming agent, 1.5 parts by weight of the surfactant, 3 parts by weight of the nano-silica, and 50 parts by weight of the solvent, and set aside. The molybdate is ammonium molybdate; the organosilicon is phenyl silicone oil DC-556; the film-forming agent is polyvinyl alcohol 1799; the surfactant is a mixture of sodium dodecylbenzenesulfonate and Tween-85 in a mass ratio of 1:3; the average particle size of the nano-silica is 30 nm; the solvent is a mixture of No. 200 solvent oil, ethylene glycol, and deionized water in a volume ratio of 4:3:1. Step S6: Add the main corrosion inhibitor, auxiliary corrosion inhibitor, molybdate, organosilicon, film-forming agent, surfactant, nano silica and solvent to a mixer, and stir and mix for 60 minutes at a temperature of 60℃ and a stirring rate of 1000r / min to obtain a high-temperature composite corrosion inhibitor.

[0028] Comparative Example 1: This comparative example illustrates a method for preparing a high-temperature composite corrosion inhibitor, comprising the following steps: Step S1: Weigh out 5 parts by weight of molybdate, 4 parts by weight of organosilicon, 5 parts by weight of film-forming agent, 1.5 parts by weight of surfactant, 3 parts by weight of nano-silica, and 50 parts by weight of solvent for later use; the molybdate is ammonium molybdate; the organosilicon is phenyl silicone oil DC-556; the film-forming agent is polyvinyl alcohol 1799; the surfactant is a mixture of sodium dodecylbenzenesulfonate and Tween-85 in a mass ratio of 1:3; the average particle size of the nano-silica is 30 nm; the solvent is a mixture of No. 200 solvent oil, ethylene glycol, and deionized water in a volume ratio of 4:3:1. Step S2: Add molybdate, organosilicon, film-forming agent, surfactant, nano silica and solvent to a mixer and mix for 60 min at a temperature of 60℃ and a stirring rate of 1000 r / min to obtain a high-temperature composite corrosion inhibitor.

[0029] Comparative Example 2: This comparative example illustrates a method for preparing a high-temperature composite corrosion inhibitor, comprising the following steps: Step S1: 40 mmol of 3-bromo-1-propanol, 50 mmol of triethylamine and 70 mL of anhydrous tetrahydrofuran were added to a three-necked flask equipped with a stirrer, thermometer and constant pressure dropping funnel. The mixture was stirred at 25 °C and 300 r / min for 30 min. Then, 10 mmol of phosphorus oxychloride was added dropwise while stirring, with the dropping rate controlled at 3 drops / s. After the addition was completed, the temperature was raised to 45 °C and the mixture was stirred for 8 h. After the reaction was completed, the reaction product was cooled to room temperature and then filtered under vacuum. The solvent was removed by rotary evaporation of the filtrate to obtain the tribromophosphate compound. Step S2: 10 mmol of tribromophosphate compound, 30 mmol of 5-aminotetrazolium, 45 mmol of triethylamine and 90 mL of anhydrous acetonitrile were added to a three-necked flask equipped with a stirrer, thermometer and gas delivery tube. Nitrogen gas was introduced for protection. The mixture was stirred at 5 °C and 300 r / min for 30 min. The temperature was then raised to 25 °C and stirred for 3 h. The temperature was then raised to 85 °C and stirred for 6 h. After the reaction was completed, the reaction product was cooled to room temperature and then vacuum filtered. The solvent was removed by rotary evaporation of the filtrate. The filtrate was then washed three times with anhydrous ethanol and anhydrous acetone. The filtrate was then placed in a vacuum drying oven and dried at 65 °C for 3 h to obtain the auxiliary corrosion inhibitor. Step S3: Weigh out 13 parts by weight of auxiliary corrosion inhibitor, 5 parts by weight of molybdate, 4 parts by weight of organosilicon, 5 parts by weight of film-forming agent, 1.5 parts by weight of surfactant, 3 parts by weight of nano-silica, and 50 parts by weight of solvent, and set aside. The molybdate is ammonium molybdate; the organosilicon is phenyl silicone oil DC-556; the film-forming agent is polyvinyl alcohol 1799; the surfactant is a mixture of sodium dodecylbenzenesulfonate and Tween-85 in a mass ratio of 1:3; the average particle size of the nano-silica is 30 nm; the solvent is a mixture of No. 200 solvent oil, ethylene glycol, and deionized water in a volume ratio of 4:3:1. Step S4: Add the auxiliary corrosion inhibitor, molybdate, organosilicon, film-forming agent, surfactant, nano silica and solvent into a mixer, and stir and mix for 60 min at a temperature of 60℃ and a stirring rate of 1000 r / min to obtain a high-temperature composite corrosion inhibitor.

[0030] Comparative Example 3: This comparative example illustrates a method for preparing a high-temperature composite corrosion inhibitor, comprising the following steps: Step S1: 10 mmol of 2-trifluoromethyl-4-bromopyridine, 10 mmol of 4,4'-bis(dimethylamino)benzyl alcohol, 20 mmol of anhydrous potassium carbonate, 25 mL of deionized water, and 70 mL of N,N-dimethylformamide were added to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Argon gas was introduced for protection, and the mixture was stirred at 25 °C and a stirring rate of 300 r / min for 30 min. Then, 0.7 g of tetrakis(triphenylphosphine)palladium was added, and the mixture was heated to 105 °C and stirred for another 12 h. After the reaction was completed, the reaction product was added to a saturated saline solution, and then extracted three times with dichloromethane. The extracts were combined and the solvent was removed by rotary evaporation to obtain a fluorinated bis(tertiary) amine compound. Step S2: 10 mmol of a fluorinated bis-tertiary amine compound, 25 mmol of potassium hydroxide, and 100 mL of dimethyl sulfoxide were added to a three-necked flask equipped with a stirrer, thermometer, and constant pressure dropping funnel. The mixture was stirred at 25 °C and a stirring rate of 300 r / min for 30 min. The temperature was then raised to 95 °C and the mixture was stirred for 3 h. Then, 20 mmol of benzyl chloride was added dropwise while stirring, with a dropping rate of 3 drops / s. After the addition was complete, the mixture was stirred for 15 h. After the reaction was completed, the reaction product was cooled to room temperature and then added to anhydrous tetrahydrofuran. The mixture was allowed to stand to precipitate, and then vacuum filtered. The filter cake was placed in a vacuum drying oven and dried at 65 °C for 3 h to obtain the main corrosion inhibitor. Step S3: Weigh out 19 parts by weight of the main corrosion inhibitor, 5 parts by weight of molybdate, 4 parts by weight of organosilicon, 5 parts by weight of film-forming agent, 1.5 parts by weight of surfactant, 3 parts by weight of nano-silica, and 50 parts by weight of solvent, and set aside. The molybdate is ammonium molybdate; the organosilicon is phenyl silicone oil DC-556; the film-forming agent is polyvinyl alcohol 1799; the surfactant is a mixture of sodium dodecylbenzenesulfonate and Tween-85 in a mass ratio of 1:3; the average particle size of the nano-silica is 30 nm; the solvent is a mixture of No. 200 solvent oil, ethylene glycol, and deionized water in a volume ratio of 4:3:1. Step S4: Add the main corrosion inhibitor, molybdate, organosilicon, film-forming agent, surfactant, nano silica and solvent to a mixer and mix for 60 minutes at a temperature of 60℃ and a stirring rate of 1000r / min to obtain a high-temperature composite corrosion inhibitor.

[0031] Performance testing The N80 steel sheet was polished sequentially with 600#, 800#, and 1200# metallographic sandpaper, then washed sequentially with anhydrous acetone, anhydrous ethanol, and distilled water, and then placed in a vacuum drying oven and dried at 60°C for 2 hours to obtain the test steel sheet. According to the SY / T5405-2019 standard, test steel sheets of the same size (50mm×10mm×3mm) were placed in hydrochloric acid solutions containing the high-temperature composite corrosion inhibitors of Examples 1-3 and Comparative Examples 1-3, respectively. The mass fraction of the hydrochloric acid solution was 20%, and the amount of the high-temperature composite corrosion inhibitor was 3% of the mass of the hydrochloric acid solution. After that, they were allowed to stand for corrosion at 100℃ and 180℃ for 4 hours, and the corrosion rate and corrosion inhibition rate were calculated using the weight loss method.

[0032] The test results are shown in Table 1 and Figure 1-2 As shown; Table 1: Test results of corrosion rate and corrosion inhibition rate

[0033] See Table 1 and Figure 1-2 As shown, based on the comparison between Examples 1-3 and Comparative Examples 1-3, it can be seen that adding auxiliary corrosion inhibitors and main corrosion inhibitors can significantly improve the corrosion inhibition effect of high-temperature composite corrosion inhibitors, and can still maintain excellent corrosion inhibition effect in high-temperature environments.

[0034] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0035] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A high-temperature composite corrosion inhibitor, characterized in that, Includes the following components by weight: The main corrosion inhibitor consists of 11-19 parts, the auxiliary corrosion inhibitor consists of 5-13 parts, the molybdate consists of 4-5 parts, the organosilicon consists of 2-4 parts, the film-forming agent consists of 3-5 parts, the surfactant consists of 0.9-1.5 parts, the nano silica consists of 2-3 parts, and the solvent consists of 40-50 parts. The primary corrosion inhibitor is prepared by the following steps: Step a1: 2-trifluoromethyl-4-bromopyridine, 4,4'-bis(dimethylamino)benzyl alcohol, anhydrous potassium carbonate, deionized water and N,N-dimethylformamide were stirred and reacted. Then tetra(triphenylphosphine)palladium was added and the reaction was stirred and reacted. After the reaction was completed, the reaction product was added to a saturated saline solution, then extracted, and the extract was evaporated by rotary evaporation to obtain a fluorinated bis(tertiary) amine compound. Step a2: The fluorinated bis-tertiary amine compound, potassium hydroxide and dimethyl sulfoxide are stirred and reacted. Then benzyl chloride is added dropwise and the reaction is continued with stirring. After the reaction is completed, the reaction product is cooled and then added to anhydrous tetrahydrofuran. After vacuum filtration, the filter cake is dried to obtain the main corrosion inhibitor.

2. The high-temperature composite corrosion inhibitor according to claim 1, characterized in that, The ratio of 2-trifluoromethyl-4-bromopyridine, 4,4'-bis(dimethylaminobenzyl alcohol), anhydrous potassium carbonate, deionized water, N,N-dimethylformamide, and tetra(triphenylphosphine)palladium in step a1 is 10 mmol: 10 mmol: 15-20 mmol: 20-25 mL: 60-70 mL: 0.5-0.7 g.

3. The high-temperature composite corrosion inhibitor according to claim 1, characterized in that, The ratio of the fluorinated bis-tertiary amine compound, potassium hydroxide, dimethyl sulfoxide, and benzyl chloride used in step a2 is 10 mmol: 22-25 mmol: 80-100 mL: 20 mmol.

4. The high-temperature composite corrosion inhibitor according to claim 1, characterized in that, The auxiliary corrosion inhibitor is prepared by the following steps: Step b1: 3-bromo-1-propanol, triethylamine and anhydrous tetrahydrofuran were stirred and reacted, then phosphorus oxychloride was added dropwise and the reaction was continued with stirring. After the reaction was completed, the reaction product was cooled, then filtered under vacuum, and the filtrate was evaporated by rotary evaporation to obtain tribromophosphate compound. Step b2: Tribromophosphate compound, 5-aminotetrazole, triethylamine and anhydrous acetonitrile are stirred and reacted. After the reaction is completed, the reaction product is cooled, then vacuum filtered, the filtrate is evaporated by rotary evaporation, and then washed and dried to obtain the auxiliary corrosion inhibitor.

5. The high-temperature composite corrosion inhibitor according to claim 4, characterized in that, The ratio of 3-bromo-1-propanol, triethylamine, anhydrous tetrahydrofuran, and phosphorus oxychloride in step b1 is 35-40 mmol: 40-50 mmol: 60-70 mL: 10 mmol.

6. The high-temperature composite corrosion inhibitor according to claim 4, characterized in that, The ratio of the tribromophosphate compound, 5-aminotetrazole, triethylamine, and anhydrous acetonitrile in step b2 is 10 mmol: 30 mmol: 35-45 mmol: 80-90 mL.

7. A method for preparing a high-temperature composite corrosion inhibitor, characterized in that, Includes the following steps: Step 1: Weigh out 11-19 parts of the main corrosion inhibitor, 5-13 parts of the auxiliary corrosion inhibitor, 4-5 parts of molybdate, 2-4 parts of organosilicon, 3-5 parts of film-forming agent, 0.9-1.5 parts of surfactant, 2-3 parts of nano silica, and 40-50 parts of solvent according to the following weight proportions, and set aside. Step 2: Add the main corrosion inhibitor, auxiliary corrosion inhibitor, molybdate, organosilicon, film-forming agent, surfactant, nano silica and solvent to a mixer and mix for 30-60 minutes at a temperature of 50-60℃ and a stirring speed of 800-1000r / min to obtain a high-temperature composite corrosion inhibitor.

8. The method for preparing a high-temperature composite corrosion inhibitor according to claim 7, characterized in that, The molybdate is ammonium molybdate; the organosilicon is phenyl silicone oil DC-556.

9. The method for preparing a high-temperature composite corrosion inhibitor according to claim 7, characterized in that, The film-forming agent is polyvinyl alcohol 1799; the surfactant is a mixture of sodium dodecylbenzenesulfonate and Tween-85 in a mass ratio of 1:2-3.

10. The method for preparing a high-temperature composite corrosion inhibitor according to claim 7, characterized in that, The average particle size of the nano-silica is 30 nm; the solvent is a mixture of No. 200 solvent oil, ethylene glycol and deionized water in a volume ratio of 3-4:2-3:1.

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